1. Field of the Invention
This invention relates to a speaker device and is suitably applied to an audio system which is installed in a vehicle, for example.
2. Description of the Related Art
As audio systems to be installed in vehicles, such systems has been popularized that a plurality of speakers are arranged not only at the front and rear cabinets of a vehicle but also at places surrounding a driver, including the inside of doors, so that the listening driver can feel of “being there”.
Out of these speakers, speakers to be installed at the doors are attached so that its vibratory plate side (hereinafter, referred to as a dry side) faces the inside of the vehicle and its magnetic circuit side (hereinafter, referred to as wet side) faces the outside of the vehicle.
Normally, because rain or car wash water enter from gaps of glass windows, the outsides of vehicle doors are provided with various waterproof functions. Considering that water enters when the windows are opened and closed, a surface facing the wet side of a speaker to be installed is covered with a rain cover.
Conventionally, as cone speakers to be installed on doors of this type, cone speakers (hereinafter, referred to as wet speakers) in which a lead line drawn from a voice coil is wired so as to be contained on the wet side are mainly used. Recently, however, such speakers (hereinafter, referred to as dry speakers) that a lead line drawn from a voice coil is wired so as to be drawn to the dry side via a coil vibratory plate are also used in many cases.
That is, as shown in FIG. 1, the wet speaker 1 has a conic cone vibratory plate 2 with its end opened. The outer circumference of the cone vibratory plate 2 is supported via a gasket 5 by an edge 4 formed on a frame 3. The opening of its inner circumference is supported by a damper 6 attached to the frame 3, so as to be movable forwards and backwards to the frame 3.
The bottom of the opening of the cone vibratory plate 2 is fixed to a cylindrical voice coil bobbin 8 having wounded thereon a voice coil 7 comprising a lead line. Above the opening, a hemisphere head cap 9 is attached with its projecting side facing outwards so as to cover the opening, thereby preventing deformation of the cone vibratory plate 2 in the radial direction and preventing dusts from entering inside.
In addition, to the bottom of the frame 3, a magnetic circuit 10 to vibrate the cone vibratory plate 2 forwards and backwards is fixed. This magnetic circuit 10 is composed of a disk yoke 11 with a column pole piece 11A placed at the center, on the top surface, a toric magnet 12 surrounding the outer circumference of the yoke 11, and a toric plate 13 laminated and fixed on the magnet 12.
The magnetic circuit 10 is attached to the frame 3 so that the top surface of the plate 13 is fixed to the bottom of the frame 3, and the voice coil bobbin 8 having the voice coil 7 wounded thereon is held in a contactless manner in a magnetic gap g formed between the pole piece 11A and the plate 13.
Therefore, in the wet speaker 1, when electromagnetic force is applied to the voice coil 7 according to applied current based on an audio signal externally supplied, the voice coil 7 and the magnet 12 attract or repel each other, thereby generating a sound wave according to the audio signal by vibrating the cone vibratory plate 2 forwards and backwards.
In this wet speaker 1, a connector (hereinafter, referred to as wet side connector) 14 having a plurality of connecting terminals provided thereon is provided on a projecting part 3P projecting from the outer circumference on the bottom of the frame 3. In addition, wires drawn from playback devices (not shown) such as external Mini Disc (MD) players and tuners are connected to the connecting terminals.
In this wet side connector 14, a harness 15 is drawn from each connecting terminal and the harnesses 15 are connected so as to be conducted to the lead line 7A of the voice coil 7.
In FIG. 2 where the same reference numerals are applied to parts corresponding to those of FIG. 1, the dry speaker 20 is identical to the above-described wet speaker 1 (FIG. 1), excepting for the shape of a frame 21 and the drawing state of a lead line 7A of a voice coil 7.
In this dry speaker 20, a connector (hereinafter, referred to as a dry side connector) 22 with a plurality of connecting terminals is provided on a projecting part 21P projecting from the outer circumference of the top of the frame 21. And wires drawn from playback devices (not shown) such as external MD players and tuners are connected to the connecting terminals.
In this dry side connector 22, a harness 23 is drawn from each connecting terminal and the harnesses 23 are connected so as to be conducted to the lead line 7A of the voice coil 7 through a prescribed part 2H of the cone vibratory plate 2 (Refer to Japanese Patent Laid-Open No. 7-274285).
By the way, although many genuine cone speakers to be installed in manufacturing stage of vehicles are wet speakers, various makers mainly produce dry speakers as cone speakers.
Therefore, in a case where the user replaces a wet speaker installed in a door of his/her vehicle, with a desired dry speaker, he/she has to change connection of harnesses conducted to the lead line of the voice coil from the wet side to the dry side. This work is very troublesome for the user and a worker, and becomes a problem.
In addition, in a case where the connection of the harnesses conducted to the lead line of the voice coil is changed to the dry side via the wet side connector, the wet side connector contacts the rain cover. This makes the attachment of the speaker difficult and generates rust due to beading. In addition, if the user forcedly changes the connection of the harnesses, the speaker may be easy to come off.